This invention relates to a process for converting intermediate olefins, e.g., C.sub.5 -C.sub.12 linear mono-alkenes, in contact with a shape selective porous zeolite catalyst to provide lower olefins and isoalkene hydrocarbon products, especially propene, butenes and C.sub.4 -C.sub.7 tertiary alkenes.
Restrictions on the lead and aromatics content of gasoline fuels has created demand for improved processes which upgrade olefins to high octane components. One such class of materials is aliphatic tertiary ethers, such as methyl tert-butyl ether (MTBE) and tert-amyl methyl ether (TAME). However, the availability of isobutylene and isoamylene feedstock for these ethers is limited, and processes for making these olefins from readily available feedstocks are sought.
Recent developments in zeolite catalysts and hydrocarbon conversion processes have created interest in utilizing olefinic feedstocks, such as petroleum refinery streams rich in olefins, for the production of C.sub.4.sup.+ tertiary olefins. The C.sub.5 -C.sub.7 light naptha range product of FCC operations is rich in normal and branched mono-alkenes.
Shape selective medium pore zeolites have been demonstrated to have catalytic properties for various types of hydrocarbon conversion. It has been discovered that certain zeolites, such as recently developed MCM-22, are effective catalysts for converting these intermediate olefins to propene and lower isoalkenes at high selectivity.